1. Field of the Invention
This invention relates to sub-frames for use in the installation of windows in buildings.
2. Description of the Prior Art
In the installation of a window in a building a sub-frame is secured in an opening in a wall of the building to provide a mounting for a glazed window which is either fixed or hinged to the sub-frame. The sub-frame presents a rectangular opening for the window and comprises two spaced vertical members constituting jambs and two spaced horizontal members the lower one of which constitutes a sill.
The invention is primarily concerned with sub-frames for use in buildings having cavity walls comprising an inner skin and an outer skin with a cavity between them. Conventionally, a load bearing lintel, separate from the sub-frame is incorporated in the wall above the opening.
The present invention has for its object to simplify the installation of windows in buildings by the provision of an improved form of sub-frame.